Mullerian Inhibiting Substance (MIS), a member of the TGF-beta family, has advantages as a potential, non-toxic therapeutic to treat certain cancers originating in human reproductive tissues. Recent research results show that MIS can elicit a similar apoptotic response in cancer cells as it does in normal embryonic tissues causing regression of the Mullerian duct during early fetal development. Development of MIS as an anticancer drug has been inhibited, however, by the inability of CHO cell cultures to yield adequate levels of rhMIS protein for clinical and commercial development. The research proposed here, therefore, aims to develop an alternative tobacco plant-based expression system for commercial production of human MIS. CropTech has previously expressed several other bio-active human proteins in its proprietary plant expression system and our preliminary work in collaboration with the MIS research group at Massachusetts General Hospital has, likewise, generated transgenic tobacco lines that express and process the human MIS protein. The next steps that need to be accomplished are proposed as the objectives of this Phase I SBIR project; namely, to purify and further characterize the biochemistry of the plant produced hrMIS, to analyze the bio-activity of plant hrMIS, and to develop new rhMIS tobacco plant lines that incorporate recent technical advances that enhance tobacco-based production and purification of complex recombinant proteins. Completion of these objectives would lay a solid foundation for a follow-up Phase II program focused on scaling up MIS production, animal studies, toxicology trials and initiation of clinical trials with tobacco- synthesized MIS protein. PROPOSED COMMERCIAL APPLICATIONS: Development of MIS as an anti-cancer drug is currently limited by the inadequacy of existing biopharmaceutical technology to meet MIS product requirements for clinical and commercial development. This project could help fill this need and simultaneously develop an alternative economically viable healthy use for tobacco.